1. Field of the Invention
This invention relates to an improvement in a process for the production of linear alpha-olefins. More particularly, it relates to an improvement in a process for the conversion of ethylene to oligomers by contact with a catalytic nickel complex dissolved in a polar organic solvent.
2. Description of Prior Art
Linar monoolefins are compounds of established utility in a variety of applications. Terminal linear monoolefins, particularly those of 14 to 20 carbon atoms per molecule, are known useful intermediates in the production of various types of detergents.
It is known that ethylene can be oligomerized to higher molecular weight linear monoolefins. A variety of suitable oligomerization catalysts and processes are known. This invention is concerned with an improvement in oligomerization processes in which ethylene is converted to higher linear alpha-monoolefins by contact with a catalytic nickel complex dissolved in certain polar solvents.
One group of known nickel complex catalysts for ethylene oligomerization is prepared as the reaction product of a olefinic nickel compound and a suitable bidentate ligand. Olefinic nickel compounds used in the preparation of such catalysts are zero-valent nickel compounds such as bis(cyclooctadiene)nickel(0) or .pi.-allyl nickel compounds. Such catalysts and their use in ethylene oligomerization are described in the following patents: U.S. Pat. No. 3,644,564 to Van Zwet et al.; U.S. Pat. No. 3,647,914 Glockner et al.; and U.S. Pat No. 3,647,915 to Bauer et al.
In a different method of preparing similar nickel complex catalysts, the complex is prepared by contacting in certain polar organic solvents in the presence of ethylene (1) a simple divalent nickel salt which is at least somewhat soluble in the solvent, (2) a boron hydride reducing agent and (3) a suitable bidentate ligand. Preparations of catalysts of this type and their use in ethylene oligomerization are described in the following U.S. Pat. Nos. 3,676,523; 3,686,351 and 3,737,475, all to R. F. Mason and 3,825,615 to Lutz.